Modern coating apparatuses, especially printing machines, use closed chambered doctor systems, because the use of chambered doctor apparatuses makes it possible to achieve a uniform coloring of the transfer rolls at higher production speeds. Such an apparatus is shown in the European patent application EP 1 825 922 A2. With this known apparatus, the coating medium can be applied uniformly onto a web independent of the coating speed, whereby air inclusions in the coating mass are prevented. The good coating results are, however, not always reproducible.